PCNA and cancer: In addition, higher PCNA expression has been shown to be a poor prognosis marker for cancer patients, particularly in breast cancer [31], [33], [34], [35]http://www.pnas.org/cgi/content/full/103/51/19472?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=1&andorexacttitle=and&andorexacttitleabs=and&andorexactfulltext=and&searchid=1&FIRSTINDEX=0&sortspec=relevance&volume=103&firstpage=19472&resourcetype=HWCIT - B5#B5.